Single photon emission computed tomography (SPECT) is a non-invasive imaging system for detecting photons that are emitted from a radioactive substance, such as a molecular probe, that has been administered to an individual. Clinically, SPECT is useful in oncology for determining, grading, and locating tumor mass and evaluating its malignancy before and after treatment. Radio labeled probes produce a continuous signal, independent of any underlying molecular interaction via radioisotope decay.
Optical planar imaging/tomography (OT) is an alternative noninvasive and nonhazardous molecular imaging system, which detects light that is propagated through a tissue at single or multiple projections. Fluorescence mediated optical imaging can localize and quantify fluorescent probes present in tissues at high sensitivities and at millimeter resolutions, which make it a very useful tool for imaging breast cancer, brain function and gene expression in vivo. Optical imaging uses activatable probes that produce detectable signals upon interaction with a target.
The present invention is drawn to a combination of SPECT and OT systems whereby the SPECT system is equipped with any type of known collimator (in case of small animal imaging a multi-pinhole type is used most effectively and used in the following exemplarily as one possible embodiment) and the OT system is of very thin extension and allocated within the field-of-view of the SPECT camera and between the imaged object and the SPECT collimator.
Since both regional distribution and time variation of the underlying multivariate photon distributions are acquisition and subject specific and diversified by variations thereof, and imaging procedures cannot be performed repeatedly at short time intervals on the same living object in many cases, combined and simultaneous imaging is needed and possible with this novel device carrying clearly advantageous potential. Further advantages are simultaneous recording of tracer kinetics, less subject encumbrance, and identical imaging geometries. The proposed nuclearoptical tomographic imaging system has the potential to accurately quantify fluorescence and bioluminescence in deep heterogeneous media in vivo. The inventive apparatus supports the development of generalized reporter probes.